Defluorination of hf alkylation reactor product



Jan. 15, 1963 P. H. JOHNSON 3,073,878

DEFLUORINATION GF HF ALKYLATION REACTOR PRODUCT A T TORNEYS REAC'TQR 4HEM/IER Jan. 15, 1963 P. H. JoHNsoN DEFLUORINATION OF HF ALKYLATION REACTOR PRODUCT Filed April 5, 1960 5 .Sheets-Sheet 2 R E) ma R F LF YIM-W 3 C :35 A F 2 .F A 6| 5 O .bl I 5 1 4 m am man mbm 3%. m 5

2 3 (l mi Y 5F 5H am( 5 7 2 f A /F 9 T 5M 8l Ul 2 l wN Z n-Omn m0 .IS y 3 m 3% 3P a 3 n m 4 Y 2 a 4 R 3 4 m INVENTOR. RH, JOHNSON BY #We A TTGRNE V5 3,073,878 Patented Jan. 15: 1953 1 2 3 073 878 i eifective because of the limits on the temperature which can be attained in the reboiler. The addition ofHF to DEFLUORINATION OF HF ALKYLATION REACTR PRODUCT the reboiler of such distillation step catalyzes the de composition of the organic iuorides so that substantially Panl'H. .I hns r o un Baegwue Okla assigner to Phillips 5 complete decomposition of the HF-containing compounds Petroleum Company, a corporation of Delaware Filed Api- 5, 1960, ser. No 29,096 is accomplished. The HF, after catalyzing the decomposi- 7 Claims. (Cl, 26o- 683.433) tion reaction then passes up the column and is condensed in the overhead product'` accumulator as a separate liquid '.fliis invention relates to the treatment of organic ma- 'phase which is .heavier than the liquid hydrocarbon phase. terials to remove therefrom ilumine-containing com- 10 The'HF is theufemoved from the accumulator and repounds. In one aspect this invention relates to an imturned to the reboiler. .Excess HF, over that required to proved method for removing ilumine-containing comcatalyze the delluorination reaction, ca-n be returned to the P0UDCiS fI01T1 the hYdfOCarbOn prOduCtS-Of a hydrocarbon alkylation reactor. At the start-up of the process it is conversion process wherein anhydrous HF is used as a 'necessary-to inject substantially pure HF into the reboiler conversion catalyst. In another aspect thisinvention is to catalyze ythe deuorination reaction until suicient concerned with a combination of related and co-operative liquid HF is condensediinthe accumulator to continue steps whereby the process of deuorination of the hydrothe process. .After the initialinjection of HF, the fluorine carbon is more completely and more eiliciently performed. content of the feed is usually more than sufficient to pro- In a process for the conversion of hydrocarbons Wheref vide the HFvrequired for the defluorination reactom The in anhydrous hydrogen uoride (HF) is employed as a linvention is applicable not only to treating a contaminatcatalyst there inevitably occur' side rea-ctions in addition ed hydrocarbon in a distillation column but to treating an to the desired conversion reaction. -For example, hydroorganic iluoride-containing vhydrocarbon in a contacting gen fluoride reacts with some of the hydrocarbons to form Zone with HF at elevated temperature. organic uoides The temperature required tocatalyze the reaction will In an HF alkylation reaction, for example, the alkylabe in the range of about 150 F.-to 450 F. and the pretion of isobutane with a buetene to form isooctane, the fen-ed range will be that employed in the reboilers of reactor eluent is fractionally distilled to remove lowthe distillation steps followingvan alkylation reaction boiling hydrocarbons from the alkylate. In those inwhich is about 200 F. to 400 F'.V stances where the low-boiling hydrocarbons are recycled Ordinarily, in an HF alkylation process wherein the iirst to the process or utilized as fuel, the presence .therein fractional distillation step is for-the purpose of removing of organic lluorides poses no problem. However, in those hydrocarbons lighter than alkylate overhead, this .overinstances wherein the low-boiling hydrocarbons areutihead stream Will continue about 1000 t0 about 1200 lized as a product, it is often necessary that thesehydrop.p.m. of il'uorine in the form of uorine-containing comcarbons be substantially free from hydrogen fluoride or' pounds such as alkyl uorides." By zutilizationof this Organic llofides v 35 invention the uorine-containingcompound content It is therefore a principal object of this invention lto proof this stream is reduced to about 200 to about 300` p.p.m. Vide a method fol IemOViIig UOfiIle-CODaiIliHg C0111- Thisfreduction in uorine-containing compounds is ac-` pounds from low-boilinghydrocarbons recoveredfrom an complished Without changing the operating conditions of HFalkylation process. It is also an object of this inventhe alkylating process orl of ,the kfractional distillations tion to provide a method for removing fluorine-contain- 40 steps which follow, and merelyv involves a phase separall COHIPQPHS from lfOCiUCSv 0f HF alkylation and retion in the distillation overhead accumulator a nd Vpasv -covery resulting'hydrogen fluoride for reuser'in the proci sage of the accumulated liquid HF tothe reboiler of the.

tion;

ess'. lOtherobjects and advantages will become `apparent distillation step.jWhen the viuoride content of the hydrol0 011e Skilled iD the aft 'HP0n Study 0f vthe dSelQSllre, carbon is-lower than 100()` to l20(lp.p.m. thenreductionin including the detailed description of the invention and the lluoride kcontent by the practice of the invention Willibe 'ataehed'dfewil'ig Whefeil' v V i proportionatelyl as great as when the fluoride content is TFIGURE l-'is agschematicilowsheetof an'HFalkyla-Q.: 100 to 1200 ppm, 1 tion process having embodied ,therein the present inveni In the'sehematicow sheet of the HF alkylation procv w l vess of FIGURE Lathe alkylation reactantsienterthe'sysf a .Y FIGURE'Z-Lisa more detailed Schematic flow sheet' of 50 tem via conduit 11, :These reactants comprise a paraiin the SePS ,Whieh comprise the invention; v hydrocarbon'having at least one, tertiary carbon atom per FIGURE 3 Villustrates One method for SifiPPing the molecule andan alkylating agent vsuch as anV olefin. v For .Propane aildiightei Stream; and p Ytheusake of simplicity in this description various valves,

IFIGURE`4 illustrates a modication of the invention. pumps and other auxiliary equipment will not be illusf-v Iv have now discoverednthat organic fluoridesrfcan be trated, but those skilled in theart will readily be able Yto .substantiallly completely/ decomposed inV a unitaryfprocess supplythese because the alkylationreaction is well-known by a novel combination Aof integrated stepS, I `h11 SaC v inthe art;V Also forthe salieof simplicity,-thereaction 'cording tothis.v invention, an organic .fluoride-containing l will be describedV as applied to isobutaneand isobutylene stream, e.g.`,the'overhead-product from a fractional disalthough it is to be understood' thattheyreactionjis not Y `tillatilou,stepfollowiug'fthe alkylation reaction,c an. be-I 60 .limitedftheret0. These reactants pass intojreactor'l condensed sofas forma liquidlhydrocarb'on phase and wherethey are intimately. mixed with hydrolluoric acid ,''l' uid'HF phase;l and at leasttaiportionoftheI-IAF phase A i i step.

reboiler 26 of fractionator 19. AIsobutane and lighter hydrocarbons are passed via conduit 24 to fractionator 27 wherein a fractional distillation removes propane and lighter products overhead via conduit28, cooler 29, accumulator 31 and conduit 32. This overhead product can be stripped to remove HF, which is present in a small amount because the feed to fractionator l27 was saturated with HF at the conditions existing in accumulator 23. FIGURE 3 illustrates one preferred method for stripping the HF from this stream, although other stripping methods can be employed if desired.

Isobutane is removed as the kettle product from fractionator 27 via conduit 33 and is recycled to conduit 11 where it joins the feed to reactor .13. Aportion of the kettle product is reboiled in reboiler`3t and returned to fractionator 27.

The kettle product `from fractionator 19-is removed via conduit 35 and passed to fractionator .S6-wherein a fractional distillation removes normal butane overhead via conduct 37, cooler 3'3, accumulator-39 and conduit 41.

Alkylate product is removed from fractionator 36 via conduit 42. A portion of the .alkylate productiis reboiled in reboiler 43 and returned to fractionator 36.

Referring now to FIGURE 2, the reactor 'eluent passes to settler 16 via conduit 15 and a phase separation occurs in settler v16. Liquid HF is removed from the bottomof theV settler. Liquid hydrocarbons are removed from the settler via conduit 17 and passed via pump 20, heater 18, andconduit 17a to fractionator 19 which is operated-as a deisobutanizer, removing isobutane `and lighter materials `as overhead'product via conduit 21 and cooler 22 to accumulator A23 wherein a phase separation occurs. Isobutane` and lighter -hydrocarbons are removed from theupper liquid layervia-'conduit 24 and passed to further separation stepsas indicatedin FIGURE 1. Liquid vHF is removed from -the lower liquid layer via conduit -25 and passed towreboiler Y A26 so as to catalyze the decomposition of fluorine compounds in `reboiler 26 and fractionator 19.A The'HF passes up through fractionator 19 and is condensed and collected in accumulator 23. The kettle product comprising substantially fluorine-free normal `butane andY heavier hydrocarbons is passed viaaconduitGS to further separa tion-steps as indicated'in FIGURE l. 1

FIGURE 3 illustrates onemetho'd for.stripping dissolved HF fromthe'Cg and lighter stream removed from fractionator 27 ofFIGURE 1. The C3 and lighter products are removed overhead from depropanizer 27 via conduit 28, cooled in heat exchangerf29 and passed to 'accumulator 31 Where any freerHF forms-a separate liquid phase below the hydrocarbon phase. The hydrocarbon phase is passed via conduit32 -to HF stripper '51,. -HF free'Caand lighter products are removed'from the kettle orbottom of the stripper via conduit 52 and passed tostorage `or use. The stripper overhead product 'comprising HF is removed'viavconduit 53, cooled in heat exchanger 54'and passed to accumulator 31. Liquid HF is withdrawn from accumulator 31 via conduit'55` and passed to reboileri26 of -fractionator 19 or to reacto`r1'3 as desired. A portion of the hydrocarbon `stream is' diyerted from conduit 32 via conduit 56 as redux for fractionator27. Such reu'x 'is conventional on all of `the fractionatorslillustrated. The kettle of stripper 51 can on the first fractional distillation step and comprises condensing the fractionator overhead product, collecting the condensate in an accumulator wherein a liquid phase separation occurs, and returning the acid phase, or at least ,a portion thereof, to the reboiler of the first fractional distillation step. In some installations, it may bc desirable to divide the reactor efiluent so that one portion passes to a depropanizer and a second portion passes to a deisobutanizer, in which case uorine compounds would be present in the feed to each distillation step and the invention would be practiced on cach distillation step.

FIGURE 4 illustrates a modification of the invention wherein the reactor eiiluent stream is divided between a depropanizer and a deisobutanizer. The stream in conduit 17 is divided so that a first portion of the stream passesvia conduit 6) and heater 61 to depropanizer 62 and a second portion passes via conduit 63 and heater 64 to deisobutanizer 65. The overhead from depropanizer 62 passes via conduit 66 and condenser 67 to accumulator 68 where ra'liquid phase separation occurs. Propane and lighter materials are removed via conduit 69. Liquid HF is removed via conduit 70, a first portion being passed via conduit 71 to reboiler 72 of depropanizer 62. The kettle product from 62 is passed `via conduit 74 to the feed conduit 63 of deisobutanizer 65. A portion of the kettle product is diverted via conduit 75 to reboiler 72.

The overhead product from deisobutanizer passes via conduit 76 and condenser 77 to accumulator 73'Where a phase separationl occurs. Isobutane and lighter materials are removed via conduit 79 and recycled to the alkylation reactor. Liquid HF is removed via conduit S0. Excess HF removed from conduit is passed to conduit 80 -via conduit 81. HF acid is passed via conduits 80, 82and 83 to reboiler 84 of deisobutanizer 65. i Excess acid over that required in reboilers 72 and 84 continues via conduit 80 to be reused in the alkylation reactor. The kettle product from deisobutanizer 65, comprising normal butane and alkylate is passed via conduit 85 for further processing. The propane stream in conduit 69 andthe alkylate stream in conduit 85 are substantially free of organic iluorides. l

In some installations wherein the rst distillation step is a depropanizing step and the overhead products from `lation of the invention are described herewith with reference to FGURE 1, but it is to be .understood that these `operating conditions are exemplary and are not to be construed as unduly limiting the invention. Reactor 13 isoperated at a temperature of 75 and 175 p.s.i.a. The temperature ofthe feed to fractionator 19` `is raised to 165 F. and 4fractionator `19 is operated at a bottom temperature of 300"` F., a top temperature of 1604 F..

and atop pressure of p.s.i.a. Accumulator 23'1's `operated at 85 F. andj55, p.s.i. a. Fractionator27isoperated'atl a 'bottom temperature of220` jF., a top temt'ionalzdistillation step is that of removing isobutaneand lighterv materials overhead and propane and'lighter prodi hcts" are removed as the' overhead product `inthe second .fractional .distillation step linjfractionator V27. A some "installations` the "rst fractional distillation stepvis ja de,-

prop'anizfing step `whereinftheoverhead'iproductj` comprises i propaueland lightedrmaterials and the is'obutafnefis sepas rated from the alkylate'fin `afsub's'f'equent distillation step.

In 1any event, the present invention is sua'llypracticed 1 to fthe Afractior'iator;'."QItis preferred that about`llt'o about 5 volumejpercenh based on, thefeed `to th'effrac-` 75 tionater, iofj'I-IF be `added to the fra'ctionaior reboiler.

Accumulatorl is operated at 85 Ffand 150 p.s.i.a.

. Fractionator'36 is operated at a bottom" temperature of :335jF., a top temperature of`145 Pfand a'toppressurepf. fp.s.i.:ia` .y Accu,mulatorr39A ,is operated at 85?. Y The amount'r ofHFjrequiredto ,accomplishV the ,decomthe order of 1 -2,yolume,percent ofthe' hydrocarbon feed position of'the alkyluorides is `quite smal1being `in` envases The invention is not limited to these small amounts, however, since an excess of HF does no harm and merely occupies fractionator space. Thus, the critical limitation on the HF added is that at least about 1 volume percent, based on the hydrocarbon feed to the fractionator, over the amount required to saturate the hydrocarbon of HF be added to the fractionator reboiler.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of the invention.

That which is claimed is: v

1. ln a hydrotluoric acid alkylation reaction wherein the reaction eiiluent, consisting essentially of hydrocarbons and a minor amount of organic ilumine-containing compounds, is distilled in a distillation step including reboiling at least a portion of the kettle product to recover hydrocarbons lighter than aikylate as overhead product, the improvement comprising condensing the overhead product to form a liquid hydrocarbon phase and a liquid hydrotluoric acid phase; recovering the liquid hydrocarbon phase as overhead product of reduced organic lluorinecontaining compounds content; recovering the kettle product; and passing a stream consisting essentially of kettle product and said liquid hydroiiuoric acid to the reboiler section of the distillation step said acid being in an amount of at least about 1 volume percent, based on the hydrocarbon feed to the distillation step, over that required to saturate the hydrocarbon feed to the distillation step.

2. ln the process of alkylating a paraffin with an alkylating7 agent in the presence of a hydroiluoric acid catalyst wherein the reaction product, containing organic lluorine compounds, is passed to a heating step and to a fractional distillation step, including reboiling at least a portion of the kettle product, to vapor-izo and remove therefrom materials lighter than alkylate, the improvement comprising condensing the vaporized material; collecting the condensateso as to form a liquid hydrocarbon phase and a liquid hydrouoric acid phase; recovering the hydrocarbon phase as a product of the process of reduced organic iluorine compounds content; and passing a stream consisting essentially of kettle product and said liquid hydrouoric acid phase to the reboiling step of the fractional distillation step said acid being in an amount of Vat least about 1 volume percent, basedon the hydrocarbon feed d to the distillation step, over that required to saturate the hydrocarbon feed to the distillation step. l

3. The process of claim 2 wherein the acid phase passed to the reboiling step is from about 1 to about 5 volume percent, based on the feed to the distillation step, over that required to saturate the feed to the distillation step and the acid phase in excess of this amount is returned to the alkylating process.

4. rthe process of claim 2 wherein the reaction product is passed to a depropanizing distillation step.

5. The process of claim 2 wherein the reaction product is passed to a deisobutanizing distillation step.

6. The process of claim 2 wherein the reaction product is divided into two streams, one of which is passed to depropanizing distillation step and the other of which is passed to a deisobutanizing distillation step.

7. A process for reducing the organic uorine-coutaining compounds contact of a hydrocarbon material containing same which comprises:

(l) passing said hydrocarbon material containing a minor quantity of said organic duerme-containing a kettle product reboiling zone;

(2) condensing the overhead product from said distillation step to form a liquid l-iF phase and a liquid hydrocarbon phase;

(3) recovering the liquid hydrocarbon phase as overhead productof reduced organic uorine-eontaining compounds content; and

(4) passing liquid HF from said liquid HF phase to the kettle product reboiling zone of the distillation step in an amount of at least about 1 volume percent, based on the hydrocarbon feed to the distil lation step, over that required to saturate the hydrocarbon feed to the distillation step thereby heating said liquid HF passed to said zone to an organic ilumine-containing compound decomposition ternperature.

References Cited in the file of this patent UNITED STATES PATENTS Leatherman Apr, 28,

UNITED STATES PATENT OFFICE CERTIFICATE 0E CORRECTION Patent Noa 3,073,878 January l5, 1963 Paul Ho Johnson It is hereby cer* tfied that error a ent requiring correction and that these ppears in the above numbered patcorrected below` id Letters Patent should read as Column 6,

line l5,v before 1" line l8 for depropanzng" insert a Contact read -,-eontent --v Signed and sealed this 3rd day of September 1963.,

(SEAL) Amst:4

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. IN A HYDROFLUORIC ACID ALKYLATION REACTION WHEREIN THE REACTION EFFLUENT, CONSISTING ESSENTIALLY OF HYDROCARBONS AND A MINOR AMOUNT OF ORGANIC FLUORINE-CONTAINING COMPOUNDS, IS DISTILLED IN A DISTILLATION STEP INCLUDING REBOILING AT LEAST A PORTION OF THE KETTLE PRODUCT TO RECOVER HYDROCARBONS LIGHTER THAN ALKYLATE AS OVERHEAD PRODUCT, THE IMPROVEMENT COMPRISING CONDENSING THE OVERHEAD PRODUCT TO FORM A LIQUID HYDROCARBON PHASE AND A LIQUID HYDROFLUORC ACID PHASE; RECOVERING THE LIQUID HYDROCARBON PHASE AS OVERHEAD PRODUCT OF REDUCED ORGANIC FLUORINECONTAINING COMPOUNDS CONTENT; RECOVERING THE KETTLE PRODUCT; AND PASSING A STREAM CONSISTING ESSENTIALLY OF KETTLE PRODUCT AND SAID LIQUID HYDROFLUORIC ACID TO THE REBOILER SECTION OF THE DISTILLATION STEP SAID ACID BEING IN AN AMOUNT OF AT LEAST ABOUT 1 VOLUME PERCENT, BASED ON THE HYDROCARBON FEED TO THE DISTILLATION STEP, OVER THAT REQUIRED TO SATURATE THE HYDROCARBON FEED TO THE DISTILLATION STEP. 